Ruthenium-cobalt carbonyl catalysts for the dealkoxyhydroxymethylation of acetals to form glycol ethers

ABSTRACT

The cobalt carbonyl catalyst R 5  CCo 3  (CO) 9 , desirably with Ru 3  (CO) 12 , wherein R 5  is hydrogen; alkyl, preferably C 1-5  lower alkyl; cycloalkyl or substituted cycloalkyl; cycloalkenyl, such as cyclohexenyl or cyclooctenyl; C 1-12  alkoxy, such as methoxy or propoxy; aryl or alkyl-, cycloalkyl-, alkoxy-, halo-, or cyano-substituted aryl; cyano; or a silyl carbyne moiety of the formula R 3   6  Si, wherein R 6  is alkyl or aryl, effectively catalyzes the dealkoxyhydroxymethylation of aldehyde acetals to form glycol monoethers. Methylal, for example, may be reacted with syngas; i.e., CO and H 2 , in the presence of this catalyst system to form the corresponding ethylene glycol monomethyl ether. 
     The novel catalyst combination of R 5  CCo 3  (CO) 9  and Ru 3  (CO) 12  is likewise claimed herein.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 782,805, filed Oct. 2, 1985,and a continuation-in-part of Ser. No. 622,817, filed June 21, 1984.

BACKGROUND OF THE INVENTION SCOPE OF THE INVENTION

This invention relates to the dealkoxyhydroxmethylation of aldehydeacetals. More particularly, it relates to a novel process for thedealkoxyhydroxymethylation of certain dialkyl-, dicycloalkyl-, diaryl-,or cyclic-aldehyde acetals by reacting said acetals with syngas, i.e.,hydrogen and carbon monoxide, in the presence of carbyne-substitutedcobalt carbonyl catalysts, desirably in combination with a rutheniumcarbonyl compound, to form the corresponding glycol monoethers. Theacetals described herein may be prepared separately or formed in situfrom the corresponding aldehyde and alcohol precursors. This inventionalso relates to certain novel ruthenium carbonyl-carbyne-substitutedcobalt carbonyl catalyst compositions per se.

The glycol ethers described herein encompass known classes of compoundshaving various uses, as for example as jet fuel additives, cleaners,coatings, solvents, intermediates in the production of certaindiphthalates, and the like.

DESCRIPTION OF THE PRIOR ART

One current well-known method of manufacturing glycol monoethers such asmonoalkyl ethers consists of reacting ethylene oxide with the alcoholcorresponding to the desired alkyl ether, employing various knowncatalyst systems.

Alternatively, the cobalt-catalyzed reaction of aldehydes or theirdialkyl acetals with syngas, i.e., a carbon monoxide-hydrogen mixture,to form the corresponding glycol ether is also described in the art.Thus, for example, a method of making ethylene glycol ethers isdescribed in U.S. Pat. No. 2,525,793 which employs cobalt oxide tocatalyze the reaction of methylal with syngas to provide a reactionmixture which, after hydrogenation over nickel, gives relativelyuneconomical conversions on the order of 25-33%.

Numerous attempts have been made to obtain more practical yields ofglycol ethers from aldehydes or their dialkyl acetals. A number ofpromoters have been used in conjunction with various cobalt catalysts inan effort to improve reaction rates and product yields. U.S. Pat. No.4,062,898, for example, discloses a ruthenium chloride-promoted cobaltiodide catalyst which hydrocarbonylates formaldehyde dimethylacetal(methylal) to ethylene glycol monomethyl ether (EGMME) in yields of 10%or less. The reaction temperature required is 185° C. at 20 atm. orabove. A second method, described in Jpn. Kokai Tokkyo Koho 81 83,432(1981) uses substantial quantities of 2,4,6- collidine or similararomatic amines to promote the cobalt carbonyl-catalyzedhydrocarbonylation of methylal in benzene as a solvent. The reaction ofmethylal with highly pressurized syngas in this process at 190° C. for10 hours gave 44% selectivity to EGMME at 98% conversion. A furtherpatent, Euro. Pat. Appln. EP 34,374 (1981) uses both iodine andtriphenyl or tricyclohexylphosphine together with RuCl₃.H₂ O to promotethe Co(Ac)₂.4H₂ O - catalyzed hydrocarbonylation of methylal using 3000psig of syngas, and temperatures of between 150° and 175° C. to obtainresults nearly comparable to those of the Japanese.

More recently, Knifton has found that cobalt carbonyl promoted with aGroup VIB donor ligand catalyzes the hydrocarbonylation of an aldehydein an alcohol to make ethylene glycol monoethers; U.S. Pat. No.4,308,403. Yields of ethylene glycol monobutyl ether (EGMBE) as high as61 wt. % were reported in this patent. A cyclopentadienyl-ligated cobaltcatalyst is also effective for these reactions giving glycol ethers inup to 54% yield; U.S. Pat. No. 4,317,943.

Propylene glycol monoalkyl ethers are formed by contacting high pressuremixtures of carbon monoxide and hydrogen with either an acetal or analdehyde and an alcohol using a cobalt catalyst promoted with a tin- orgermanium-containing compound; U.S. Pat. No. 4,356,327. Yields of glycolethers up to 31 wt. % were reported in this patent. Ethylene glycolethers were also formed from a formaldehyde acetal or formaldehyde andan alcohol using tin or germanium promoters for cobalt carbonyl; U.S.Pat. No. 4,357,477. The highest gycol ether yield (EGMBE) was 53% inthis case.

Further, propylene glycol monoalkyl ethers were formed byhydrocarbonylation of acetaldehyde acetals or acetaldehyde and alcoholsusing rhodium, ruthenium or nickel compounds to promote either cobaltcarbonyls or cobalt compounds having group V ligand systems attached.Glycol ether yields up to 28 wt. % were realized when these promoterswere used; Knifton, U.S. Pat. No. 4,390,734 (1983).

Thus, the use of various promoters for the cobalt-catalyzedhydrocarbonylation of aldehydes or acetals has resulted in glycol etheryields of from 10-61 wt. %, depending on the glycol ether produced. Thehighest reported yield of EGMME is 44%, of EGMBE is 61% and propyleneglycol monoethyl ether, PGMEE is 28%.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an improvedprocess for the reaction of certain dialkyl-, dicycloalkyl-, diaryl-, orcyclic- aldehyde acetals or their aldehyde-alcohol precursors, withsyngas in the presence of a carbyne-substituted cobalt carbonylcatalyst, R⁵ CCo₃ (CO)₉, wherein R⁵ may be hydrogen; alkyl, preferablyC₁₋₁₂ alkyl, and most preferably C₁₋₅ lower alkyl; cycloalkyl oralkyl-substituted cycloalkyl, preferably C₅₋₁₀ moieties; cycloalkenyl,such as cyclohexenyl or cyclooctenyl, preferably C₆₋₁₂ cycloalkenyl;alkoxy, such as methoxy or propoxy, preferably C₁₋₁₂ alkoxy; aryl oralkyl-, cycloalkyl-, alkoxy-, halo-, or cyano-substituted aryl,preferably C₆₋₂₀ moieties; cyano; or a silyl moiety of the formula R₃ ⁶Si wherein R⁶ is alkyl or aryl, to form the corresponding glycolmonoethers.

In a further, and preferred, embodiment of this invention it has beenfound that when the aforedescribed R⁵ CCo₃ (CO)₉ catalyst is combinedwith the ruthenium carbonyl catalyst Ru₃ (CO)₁₂, the selectivity for thedesired glycol ether is significantly increased.

The process of this invention, which may best be described as thedealkoxyhydroxymethylation of an acetal, formed separately or in situ bythe reaction of an aldehyde with an alcohol, may be depicted by thefollowing general reaction scheme: ##STR1## wherein R is hydrogen,alkyl, cycloalkyl, or aryl; R¹ and R², which may be the same ordifferent, are alkyl, cycloalkyl, or aryl, and taken together may form acyclic acetal; R³ is alkyl, cycloalkyl, aryl, or an hydroxy-substitutedhydrocarbon moiety; and R⁴ is alkyl, cycloalkyl, or aryl correspondingto whichever R¹ or R² group is displaced. In the case where cyclicacetals are employed, however, no alcohol by-product is formed.

Examples of R¹, R², R³ or R⁴ alkyl, cycloalkyl, and aryl groups whichmay be employed include such substituted or unsubstituted groups as:

(a) straight or branched chain alkyl groups, preferably those havingfrom 1 to about 20 carbon atoms, such as methyl, ethyl, propyl,isopropyl, n-butyl, t-butyl, 2-ethylhexyl, dodecyl, and the like;

(b) substituted or unsubstituted cycloalkyl groups, preferably thosehaving from about 5 to about 20 carbon atoms, such as cyclopentyl,cyclohexyl, cycloheptyl, 3-methylcyclopentyl, 3-butylcyclohexyl,cyclooctyl, adamantyl, decalyl, 3-phenylcycloheptyl and the like; and

(c) substituted or unsubstituted aryl groups, preferably those having 6to about 20 carbon atoms such as benzyl, phenyl, naphthyl, fluoranthyl,tetralyl, tolyl, ethylphenyl, cumyl, anisyl, chlorophenyl, and the like.

It will be understood that when R¹ and R² in the foregoing reactionscheme are different, the resulting product will actually be mixtures ofthe corresponding glycol ethers and alcohols. It will also beunderstood, as mentioned above, that R¹ and R² may be joined by one ormore bridging atoms to form a cyclic acetal, in which case, under theconditions of this reaction the heterocyclic ring will cleave at acarbon-oxygen bond of the acetal moiety, and hydroxymethylate, therebyforming a dihydroxy compound, i.e. an hydroxy-substituted glycol ether.

This process provides an improvement over the methods of the prior artin that the instant catalysts do not require the added presence of theiodide, amines, or phosphine promoters such as are disclosed in theprior art, and thus are less costly and easier to prepare and recover.Moreover, these novel catalysts permit the reaction to be carried outunder mild conditions of time and temperature, yet most surprisinglyprovide rates and selectivities of desired product over those obtainedby the use of cobalt carbonyl alone.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The carbyne-substituted catalyst of this invention, R⁵ CCo₃ (CO)₉,wherein R⁵ is as defined above, may be prepared in accordance with theprocedures taught in Inorganic Synthesis, Wiley-Interscience Pub., NewYork, Vol. 20, #53-B, pp. 226 et seq. (1980). As stated above, thiscatalyst may be used with Ru₃ (CO)₁₂, a known compound. When used incombination, the molar ratios of these two components should optimallybe in the range of about 10:1 to 1:10, and preferably about 5:1 to 1:5.

The acetal dealkoxyhydroxymethylation reaction with syngas, utilizingthe catalysts of this invention, may conveniently be conducted in agenerally known manner whereby the desired acetal is reacted with syngasunder elevated temperature and pressures for given periods of time,during which period the reaction mixture is actively stirred. In thisreaction, the volume ratio of carbon monoxide to hydrogen in the syngasdesirably is in the range of from about 1:5 to 5:1, and more preferably1:3 to 3:1. Following rapid cooling, the reaction product is thenrecovered from the mixture in a routine manner. In contrast to prior artreaction conditions described above, the catalysts of this inventionadvantageously permit the use of mild operating conditions. Thus,temperatures in the range of from about 100° to 200° C., and preferablyabout 125° to 175° C., pressures of from about 500 to 5000 psi, andpreferably about 1000 to 3000 psi, may satisfactorily be employed. Thereaction time is not critical, and may range up to several hours,desirably up to 5-6 hours.

The weight ratio, in grams, of catalyst mixture to acetal, is desirablyin the range of from about 1:1000-10:1, and preferably in the range offrom about 1:100-1:1 in a batch reaction.

In a further embodiment of this invention, it has been found that highlyadvantageous effects may also be obtained in thisdealkoxyhydroxymethylation process by the use of solvents with theacetal. The solvents which may be advantageously used comprise any polaror non-polar organic solvents which are inert to the conditions of thereaction. Included amongst these solvents are C₁₋₁₂ alcohols, such asmethanol, ethanol, butanol, 3-ethyl-2-hexanol and the like; ethers whichwill not cleave under the conditions of the reaction, such as glyme,diglyme, diphenyl ether and the like; aromatics and substitutedaromatics such as benzene, toluene, xylene, chlorobenzene,dichlorobenzene, anisole, and the like.

The solvents may be employed in amounts of up to 90 volume percent ofthe reaction mixture, and preferably in amounts of from about 20 to 80percent.

In still a further embodiment of this process, it has been found thatwith acyclic acetals, when the reaction is carried out in an excess ofan alcohol solvent, wherein the ratio of acetal to alcohol solvent isdesirably in the range of from about 1:2 to 1:20, and preferably 1:5 to1:10, and wherein the R group of the alcohol used is different from theR¹ and/or R² substituents on the acetal starting material, thesedifferent R groups of the alcohol will, in the course of the reaction,replace the R¹ and/or R² groups on the acetal in a substitutionreaction, thereby resulting in a glycol monoether in which the R groupof the ether moiety corresponds to the R group of the alcohol solvent.

This reaction may be illustrated by the following equation: ##STR2##wherein R, R¹ and R² are as defined above except that cyclic acetals arenot included, and R⁸ is a different alkyl, cycloalkyl, or aryl groupthan R¹ and/or R², and desirably has from 1 to about 20 carbon atoms.Depending upon the length of time the reaction is allowed to continue,intermediate mixtures of higher and lower molecular weight substituentson the acetal corresponding to both those of the R¹ and/or R² groups andthose of the alcohol solvent will be found in the reaction product.

The acetal starting materials employed in this invention have theaforedescribed general formula, namely ##STR3## wherein R, R¹, and R²are as defined above. These acetals can be prepared in a known manner,separately or in situ, as for example as described in E. V. Dehmlav andJ. Schmidt, Tetrahedron Letters, p. 95-6 (1976) B. S. Bal and H. W.Pinnick, J. Org. Chem., V44 (21), p. 3727-8 (1979) D. W. Hall, U.S. Pat.No. 3,492,356, Jan. 27, 1970, by the reaction of an aldehyde such asformaldehyde with an alcohol, or mixture of alcohols, of the generalformula R¹ OH or R² OH, where again R¹ and R² are as defined above, toform the corresponding acetal. In the case of cyclic acetals, thealcohol must be diol. Hereinafter, when the acetal is referred to, itwill be understood that the corresponding precursors, i.e., the desiredaldehyde and alcohol, are also intended to be included. As mentionedabove, the R¹ and R² substituents of the acetal may comprise a bridginggroup to form such cyclic acetals as: ##STR4## and the like, wherein Ris as defined above, and wherein X is selected from the group consistingof alkyl, aralkyl, aryl and cycloalkyl groups, preferably those havingfrom 1 to about 20 carbon atoms. As described above, cleavage of thering under the conditions of this reaction will result in the formationof the corresponding hydroxy-substituted glycol ether.

Illustrations of products thus formed from cyclic acetals include, forexample, diethylene glycol from dioxolane, the conversion of 2- or4-methyldioxolane to the corresponding hydroxy glycol ether, and thelike.

It is important, in selecting the acetal starting material, that it notcontain any substituents which would adversely affect the reaction. Inother words, the R, R¹, and R² groups should not, for example, containsuch reactive moieties as phosphine, arsine, amino, sulfido or carbonylgroups, acetal moieties, or olefins or acetylenic triple bonds. Otherlike groups will be recognized or readily determined by thos skilled inthe art of resulting in products other than the desired monoethers. Onthe other hand, halogen, alkoxy, and hydroxy moieties and the like maybe present on the hydrocarbon substituents without adverse effect.

When these acetals are dealkoxyhydroxymethylated with syngas inaccordance with the process of this invention, there is obtained thecorresponding glycol monoether in which the ether moiety will correspondto the R¹ and R² groups of the acetal starting material. Also formed inlesser amounts are a tri-substituted ethane of the general formula##STR5## wherein R¹ (or alternatively, R², or mixtures of R¹ and R²) isas defined above, which may be recycled to form additional acetalstarting material, and alcohol by-products. Again, as above, if the R¹and R² groups of the acetal are different, a mixture of correspondingR-substituted compounds will result. This tri-substituted ethane isbelieved to form during the reaction from an alkoxyacetaldehyde, e.g.,the intermediate methoxy acetaldehyde, when methylal is used,ethoxyacetaldehyde when ethylal is used, and the like.

As shown below, the selectivities for the desired monoether over thetri-substituted by-product are in the ratio of from about 3:1 to as muchas 10:1 or more.

In a preferred embodiment of this invention, the starting materials arepreferably symmetrical acetals where the R¹ and R² groups are loweralkyl groups of 1 to about 4 carbon atoms, thereby forming thecorresponding glycol mono-lower alkyl ethers such as the monomethylether, the monoethyl ether, the monobutyl ether, and the like.

Alternatively, the acetal may contain such R¹ and R² groups as naphthyland phenyl. In the case of naphthyl, the reaction, e.g., of theformaldehyde acetal with syngas will provide 2-(2-naphthyloxy)ethanol, aknown sedative, which in turn may be oxidized to the corresponding2-naphthyloxyacetic acid, a plant growth hormone.

Likewise, the dealkoxyhydroxymethylation of, e.g., the formaldehydeacetal wherein R¹ and R² are phenyl will produce 2-phenoxy-ethanol, atopical antiseptic, which when oxidized, results in phenoxyacetic acid,a fungicide. Similarly, the formaldehyde acetal wherein R¹ and R² are2,4,5-trichlorophenyl will yield, 2,4,5-trichlorophenoxyacetic acid, aherbicide. In a like manner, when R¹ and R² are p-nonylphenyl,p-nonylphenoxyacetic acid, a corrosion inhibitor and antifoaming agentin gasoline and cutting oils will be formed.

Each of the aforedescribed products may be recovered routinely bymethods well known in the art.

The invention will now be illustrated by, but is not intended to belimited to, the following examples.

EXAMPLES Examples 1-6

A series of runs was carried out in which the following generalprocedure was employed, using as the catalyst R⁵ CCo₃ (CO)₉ alone, orpromoted with Ru₃ (CO)₁₂.

To a 300 ml stainless steel autoclave equipped with a magnedrive stirrerwas charged: methylal, and catalyst. Carbon monoxide and hydrogen wereadmitted and the reaction mixture as rapidly heated to the desiredtemperature. The mixture was stirred for the designated time at reactiontemperature after which the reactor was cooled by immersion in an icebath. When the contents reached 25° C. the final pressure was recorded.After venting the gas the liquid was analyzed by GLPC.

The results are reported in Table I below. The specific reactionconditions, amounts, and the use of solvents are described in footnote(a) in this table.

                                      TABLE I                                     __________________________________________________________________________    METHYLAL DEALKOXYHYDROXYMETHYLATION.sup.(a)                                                                           YIELD CONV. OF                               CATALYST USED, MMOLES            EGMME.sup.(b)                                                                       METHYLAL                        EXAMPLES                                                                             [HCCo.sub.3 CO).sub.9 ]                                                              (C.sub.8 H.sub.13 CCo.sub.3 (CO).sub.9 ]                                                [PhCCo.sub.3 (CO).sub.9 ]                                                              [Ru.sub.3 (CO).sub.12 ]                                                              %     %                               __________________________________________________________________________    1      0.5    0         0        0      17    92                              2      0.5    0         0        0.5    44    80                              3      0.5.sup.(c)                                                                          0         0        0.5    47    73                              4      0      0.5       0        0      20    63                              5      0      0.5       0        0.5    42    79                              6      0      0         0.5      0.5    35    63                              __________________________________________________________________________     ##STR6##                                                                      .sup.(b) (moles EGMMe formed/moles methylal reacted × 110               .sup.(c) Methylal dried over activated mole sieves before run            

Example 7

In accordance with the procedure of Example 2 except that formaldehydediethyl acetal is used in place of methylal, the monoethyl ether ofethylene glycol is formed in good yield.

Example 8

In accordance with the procedure of Example 2 except that formaldehydedibutyl acetal is used in place of methylal, the monobutyl ether ofethylene glycol is formed in high yield.

Example 9

In accordance with the procedure of Example 2 except that acetaldehydediethyl acetal is used in place of methylal, the monoethyl ether ofpropylene glycol is formed as a major reaction product.

Example 10

In accordance with the procedure of Example 9 except acetaldehyde, 285mmoles, and ethanol, 470 mmoles, were used in place of acetaldehydediethyl acetal, the monoethyl ether of propylene glycol was detectedamong the reaction products.

Example 11

To a 110 ml rocking autoclave is charged HCCo(CO)₉ (0.5 mmole), Ru₃(CO)₁₂ (1.0 mmole), methylal (27 mmoles), butanol (18.2 mmoles), andmesitylene as an internal standard. Carbon monoxide (800 psig) ischarged to the reactor followed by hydrogen to a total pressure of 3200psig and the mixture rocked 150° C. for 6 hours. Standardized gc of thereaction mixture after cooling shows that the monobutyl ether ofethylene glycol is formed in good yield.

Example 12

In accordance with the procedures of Example 2, except that the cyclicacetal dioxolane is used instead of methylal, diethylene glycol isproduced as a reaction product.

What we claim is:
 1. Process for the dealkoxyhydroxymethylation of analdehyde acetal of the formula ##STR7## wherein R is hydrogen, alkyl,cycloalkyl, or aryl; R¹ and R², which may be same or different, arealkyl, cycloalkyl, or aryl, and wherein R¹ and R², taken together mayform a cyclic acetal, which comprises reacting said acetal, which hasbeen formed separately or in situ, with syngas in the presence of acatalytically effective amount of a catalyst comprising R⁵ CCo₃ (CO)₉,or R⁵ CCo₃ (CO)₉ and Ru₃ (CO)₁₂, to form the corresponding glycolmonoether, wherein R⁵ is hydrogen, alkyl, cycloalkyl oralkyl-substituted cycloalkyl, cycloalkenyl, alkoxy, aryl or alkyl-,cycloalkyl-, alkoxy-, halo-, or cyano-substituted aryl, cyano, or asilyl moiety of the formula R₃ 6_(Si), wherein R⁶ is alkyl or aryl. 2.Process of claim 1 wherein the molar ratio of cobalt to rutheniumcarbonyl components of the catalyst mixture is in the range of fromabout 10:1 to 1:10.
 3. Process of claim 1 wherein the temperature is inthe range of from about 100° to 200° C.
 4. Process of claim 1 whereinthe pressure is in the range of from about 500 to 5000 psi.
 5. Processof claim 1 further comprising carrying out the reaction in the presenceof an inert organic solvent.
 6. Process of claim 5 wherein the inertorganic solvent is a chlorinated aromatic solvent.
 7. Process of claim 6wherein the chlorinated aromatic solvent is chlorobenzene ordichlorobenzene.
 8. Process of claim 1 wherein R, R¹ and R² are alkylgroups having from 1 to about 20 carbon atoms.
 9. Process of claim 8wherein the alkyl groups are lower alkyl.
 10. Process of claim 1 whereinthe weight ratio of catalyst to acetal, in grams, is in the range offrom about 1:1000-10:1.
 11. Process of claim 1 wherein R is hydrogen,and the product is an ethylene glycol monoether.
 12. Process of claim 1wherein R is methyl, and the product is propylene glycol monoether. 13.Process of claim 1 wherein R is ethyl, and the product is a butyleneglycol monoether.
 14. Process of claim 1 wherein the reaction is carriedout in the presence of an excess of an alcohol solvent of the formula

    R.sup.8 OH

wherein R⁸ is an alkyl, cycloalkyl, or aryl, and wherein R⁸ is differentthan either the R¹ or R² group of the acetal starting material, or both,to form a glycol ether of the formula ##STR8## wherein R and R⁸ are asdefined above with the proviso that the aldehyde acetal startingmaterial is other than a cyclic acetal.
 15. Process of claim 14 whereinR⁸ is lower alkyl.
 16. Process of any of claims 1-15 wherein the volumeratio of carbon monoxide to hydrogen in the syngas is in the range offrom about 1:5 to 5:1.
 17. Process of any of claims 1-15 wherein thevolume ratio of carbon monoxide to hydrogen in the syngas is in therange of from about 1:3 to 3:1.